For the first time in 9 years…how has Delhi’s air improved so much after Diwali?

Along with Diwali, the discussion on pollution also increases in New Delhi. The day after Diwali, the debate on the increased AQI level in Delhi intensifies in the news. But this time the pollution level on the next day of Diwali has been less than last year. If 2022 is excluded, this morning was the clearest morning the day after Diwali since 2015.

According to Central Pollution Control Board (CPCB) data, the 24-hour average air quality index (AQI) after Diwali was 339 on Friday, which is better than 358 on the next day (November 13) of Diwali in 2023. The worst air quality day after Diwali was recorded in 2021, with AQI at 462.

Why was there less pollution this time?

There are many reasons for low pollution, but the most important one is the weather at this time. Last year Diwali was celebrated in November and the temperature was quite cold at this time. Last year, the minimum temperature of November was recorded at 13 degrees Celsius and the maximum was 27.8 degrees Celsius. Whereas this year Diwali has been celebrated at the end of October and the weather at this time is much warmer than before. According to IMD, this year’s October has been the hottest October in the last 73 years.

The maximum and minimum average temperatures recorded at Delhi’s Safdarjung weather station in October were 35.1 degrees Celsius and 21.2 degrees Celsius respectively. This figure is the fourth highest temperature recorded in the month in Delhi since 1901.

Actually, when the temperature is cold, a layer freezes in the air. Due to which pollution does not spread in the upper layer of the atmosphere and remains below.

The wind was also responsible

Another reason for less pollution is strong winds. Due to strong winds, pollution spread better and the polluted air did not stay at one place. The levels of small pollutants like PM2.5 and PM10, which had increased due to stubble burning and bursting of firecrackers in Punjab and Haryana on Thursday due to strong winds, decreased the next day.

Anumita Roy Chowdhury, Executive Director of Research and Advocacy at the Center for Science and Environment, told ‘Indian Express’, this time Diwali was in October, the weather has not yet cooled down. The wind speed was also favorable for reducing pollution after Diwali night. On the day of Diwali, the air quality remained ‘poor’ till noon and then became ‘very poor’ in the evening. Critical AQI levels were observed at midnight and persisted till 7 am at many stations. A significant increase in PM2.5 levels was observed at night since Diwali. It cannot be said how much the contribution of firecrackers was in this because many other factors are involved in this increase.

What was the AQI in different areas of Delhi on November 2?

According to Central Pollution Control Board’s app Sameer, today i.e. Saturday, Delhi’s AQI is 298. This figure is at 6 am.